The present invention relates generally to air conditioning and heat pump systems and more particularly, but not by way of limitation, relates to refrigerant coils and condensate drain pan structures operatively associated therewith.
The typical indoor coil utilized with heating and cooling indoor equipment is conventionally of an inverted "V" configuration defined by two multi-row, multi-circuit fin/tube refrigerant coil slabs across which air to be cooled is flowed on its way to the conditioned space served by a furnace or air handler. Indoor coils of this type (commonly referred to as "A-coils" in the air conditioning industry) are offered in various nominal tonnages, one air conditioning "ton" being equal to an air cooling capacity of 12,000 BTU/HR. Furnaces and other air handling equipment using this type of coil are normally offered to the residential or commercial customer in an appropriate range of air conditioning tonnages which are established by the size of the A-coil installed in the furnace, or other type of air handler, in conjunction with the correspondingly sized condenser side of the overall refrigeration circuitry.
A representative air conditioning tonnage range for residential furnace applications is, for example, one to five tons, while a representative light commercial tonnage range would be from five to twenty tons. Within this overall cooling capacity range, the tonnage increment between successively larger capacity A-coils is typically 1/2, 1, 21/2 or 5 tons, with the tonnage increments usually being smaller at the lower end of the capacity spectrum.
Conventional refrigerant "A" coils have been the norm in this general furnace and air handler tonnage range for many years and have been, generally speaking, well suited for their intended purpose. However, they are also subject to a variety of well-known problems, limitations and disadvantages, particularly as pertains to their manufacture and incorporation in their associated furnaces, air handlers or the like.
For example, for each A-coil within a given multi-tonnage set thereof, it has heretofore been necessary to manufacture and inventory a differently sized pair of refrigerant coil slabs. As an example, if a manufacturer produces a line of heating and air conditioning equipment having a cooling range of from 11/2 to 20 tons, there may representatively be twelve different capacity A-coils needed-e.g., A-coils of 11/2, 2, 21/2, 3, 31/2, 4, 5, 71/2, 10, 121/2, 15 and 20 ton nominal air cooling capacities. Accordingly twelve differently sized refrigerant coil slabs must be manufactured and inventoried.
This conventional necessity increases both tooling costs and manufacturing floor space requirements, thereby also increasing the overall manufacturing costs associated with the air conditioning systems into which the A-coils are incorporated. Additionally, each of the A-coils in a necessary capacity range thereof will typically have different depths in the direction of intended air flow therethrough. For example, in up-flow furnaces, progressively larger capacity A-coils will have correspondingly increasing vertical installation height requirements. This ca result in the necessity of oversizing the cabinet height of an air handler to accommodate A-coils of varying heights. Moreover, in an attempt to reduce the number of differently dimensioned refrigerant coil slabs which must be manufactured and inventoried to assemble A-coils of the necessary different refrigeration capacities, many manufacturers provide relatively large capacity increments at the upper end of their capacity range. For example, in light commercial air conditioning equipment, the highest capacity unit may be 20 tons, while the next smaller unit may be 15 tons. If the system designer determines that, for the conditioned spaced to be served by the equipment, an air conditioning capacity of 16 tons is needed, he normally must select the 20 ton unit. This undesirably results in a 25% oversizing of the air conditioning system.
Another problem associated with a conventional coil of this general type is the drain pan structure typically secured to its underside to receive and drain away condensate dripping from the exterior of the coil during cooling operation thereof. The standard drain pan conventionally used in this application is formed from drawn sheet metal, with separate drain and overflow outlet fittings welded to the pan. In order to inhibit corrosion of the pan, it is normally formed from prepainted metal material or is painted after fabrication thereof. The welds must also be leak checked and painted as well.
Additionally, the pan must be screwed in place onto the underside of its associated coil, and the finished coil/drain pan structure must then be screwed in place within the housing of the air conditioning unit, furnace or heat pump in which the coil is to be used. Thus, the fabrication of the drain pan, its connection to the coil that it serves, and the installation of the coil/drain pan assembly have heretofore tended to be laborious and relatively expensive tasks.
In view or the foregoing, it can be seen that it would be desirable to provide improved refrigerant coil and related condensate drain pan apparatus that eliminates or at least substantially reduces the above-mentioned problems, limitations and disadvantages heretofore associated with conventional "A-coils" and their related condensate drain pan structures. It is accordingly an object of the present invention to provide such improved apparatus.